The RSA algorithm was invented by Ronald L. Rivest, Adi Shamir, and Leonard Adleman in 1977 and released into the public domain on September 6, 2000.
Public-key systems--or asymmetric cryptography--use two different keys with a mathematical relationship to each other. Their protection relies on the premise that knowing one key will not help you figure out the other. The RSA algorithm uses the fact that it’s easy to multiply two large prime numbers together and get a product. But you can’t take that product and reasonably guess the two original numbers, or guess one of the original primes if only the other is known. The public key and private keys are carefully generated using the RSA algorithm; they can be used to encrypt information or sign it.
PKCS 1 and other standards contain rules for using this algorithm and the key pairs that it generates.